1. Field of the Invention
This invention relates generally to electromagnetic interference, and more particularly to evaluating electromagnetic interference.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Examples of portable information handling systems include portable notebook computers, and personal data assistants (“PDA's”). These portable devices continue to evolve with changing technology and to address the needs of users. Currently, it is not uncommon for functional issues (e.g., system malfunctions) to be experienced when a system (e.g., portable computer) is placed in close proximity to fields generated by wireless devices. Particular examples of such wireless devices that may induce system malfunctions include GSM PC Cards (which typically have an output of 1 to 2 Watts) and to a lesser extent, cellular phones.
In the past, one method for evaluating system immunity to GSM PC Cards has involved inserting a PCMCIA card (GSM PC Card) into a computer system and then exercising the card at discrete frequencies/settings. The antenna of the PC card is then manually oriented to try to induce a failure in the system (e.g., system locks up, audio buzz, video “blooming”, etc.). However, such a method is limited by the possible range of antenna orientations, and it has been observed that the level transmitting from the PC Card antenna can fluctuate as much as 20 dB with slight movements in the antenna. This transmission level fluctuation has been observed in the laboratory and indicates that antenna connection to the PC card is not always reliable and thus makes the repeatability of this type of immunity test suspect. In addition, this past method for evaluating system immunity is basically a trial and error method in which the test is run, an antenna modification made, and then the test run again.